In many electronic applications, a reference circuit is required to provide highly accurate voltage or current. Bandgap reference circuits are commonly known and used in the art of analog design to provide a reference voltage in, for example, analog to digital (A/D) converters. Such circuits are preferable over other designs because of their low power dissipation, their ability to be used in low voltage applications, and because they provide a high level of overall stability. Bandgap voltage reference circuits are typically designed to provide first order temperature compensation.
A bandgap voltage reference operates by adding a differential voltage, derived from biasing two bipolar base-emitter junctions at different current densities, to a single base-emitter junction voltage. The differential voltage has a positive temperature coefficient, while the single base-emitter junction voltage has a negative temperature coefficient. By adjusting the magnitude of one of the temperature coefficient terms, and combining the two terms in an adder circuit, the output of the adder will be temperature independent to the first order.
Various bandgap circuits designs are known and used in the art to provide a supply independent and temperature-stable voltage. However, these designs are limited in their applicability either by their high power requirements or by the complexity of their design which requires large amounts of valuable real estate on an integrated circuit. Accordingly, it is desirable to provide a relatively simple bandgap circuit design capable of providing a temperature-stable voltage while having low power supply requirements.